This invention relates to mobile communication systems, particularly for radio or telephone communications between one of several vehicles and a communication partner, such as another one of the vehicles or a central exchange or base station.
Large companies or government agencies frequently maintain large pools or fleets of vehicles such as cars equipped with radios or radio-telephones which can be used to establish quick contact between the vehicles or between a vehicle and a base station or exchange. The term "base station" refers to any type of central office which keeps in contact with the vehicle. Each car is normally equipped with a radio set (i.e. a transceiver), a service and control unit, a hearing and speaking apparatus such as an earphone-microphone handset, and an antenna. The radio set is most often found in the trunk of the vehicle, and the antenna is mounted on the rear of the vehicle because of the need to provide a short antenna connection. A cable or cable harness connects a service and control unit with the transceiver and is located either in the dashboard of the vehicle or in a bracket secured under the dashboard. Thus located, the unit makes possible to set the control adjustments necessary for establishing a radio or telephone connection in comfort. The hearing and speaking apparatus, such as a handset, is at the same time arranged within the immediate reach of the driver. In most cases it is mounted between the front seats.
With fleets having a great number of vehicles, from which connections must be established with one and the same exchange, the total costs required for these mobile apparatuses in each car are quite high. Frequently, however, only a part of the fleet of cars is in use. Hence, there are relatively long idle times for the costly equipment in the cars and the apparatuses are not sufficiently utilized.
The same problem exists in small organizations where, for example, one business car is equipped with the above-mentioned apparatus, but the same equipment would also be desirable for a personal car so that the owner could establish telephone contacts after regular business hours. However, in most cases, the personal car is not used during business hours. Hence, if both cars are equipped with a mobile communication system, this costly equipment is used inefficiently in that the operating time is insufficient.
An object of this invention is to avoid these problems. Another object of the invention is to provide a communication system which permits cost-justifying utilization of the equipment installed in the vehicles by avoiding the aforementioned long idle times.